The UK garden market is worth around £5bn, with some £1.4bn spent on garden plants by UK consumers in 2013, according to the HTA, the industry body.

The Gardeners' World presenter believes consumers should shop around.

"I'm a huge fan of independent nurseries. That is where you get the expertise, it's where you will find people who have devoted their life to growing something.

"They will grow geraniums or trees and they will really know about it, so when you contact them, they can give you great help and assistance."

Martin Simmons, HTA director of operations, said: "People often make impulse purchases of plants in supermarkets and if this then encourages them to buy more plants then this is good for the industry and helps to grow the market.

"Buying a plant in a supermarket may be the first step for some consumers, particularly younger ones. If this grabs their interest they will naturally seek out garden centres and retail nurseries."